Dry-compressing compressors are becoming ever more important in industrial compressor technology, because due to increasing obligations with regard to envonmental regulations and rising operating and disposal costs, as well as greater requirements with regard to the purity of the delivery medium, the known wet-running compressors, such as liquid ring machines, rotary vane pumps and oil or water-injected screw compressors, are replaced with dry-compressing machines with increasing frequency. Dry screw compressors, claw pumps, diaphragm pumps, piston pumps, scroll machines as well as Roots pumps are among these dry-compressing machines. However, what these machines have in common is that they still do not meet today's requirements with regard to reliability and ruggedness as well as constructional size and weight with a low price level and satisfactory efficiency at the same time.
The known dry-compressing spindle compressors are an option for improving this situation, because as typical 2-shaft displacement machines, they realize a high compression capacity simply by achieving the required multi-stage property as so-called “delivery threads” by a serial arrangement of several closed working chambers through the number of wraps per compressor rotor in an extremely uncomplicated manner, without, however, requiring an operating fluid in the working space. Moreover, the contactless rolling of the two counter-directionally rotating spindle rotors enables an increased rotational speed of the rotors, so that the nominal suction capacity and the volumetric efficiency are increased at the same time, relative to the constructional size. In this case, dry-compressing spindle machines can be used for application both in a vacuum as well as in overpressure conditions, with the power requirements in overpressure conditions of course being significantly higher because, in the overpressure range with final pressures significantly greater than 2 bar (absolute) to up to 15 bar and more, greater pressure differences have to be overcome.
For a dry-compressing spindle compressor, German patent application no. DE 10 2013 009 040.7 describes how a large internal compression ratio as well as a high number of stages is obtained with non-parallel rotation axes of the two spindle rotors, while at the same time minimizing the internal leakage between the multiple series-connected working chambers between the delivery gas inlet and the outlet. In the case of compression refrigeration machines, compressor technology for this power range is still dominated by screw compressors that require an operating fluid in the working space, with the desired power adjustment most frequently taking place by means of complex control slide valves. Moreover, 2 series-connected compressors are frequently required for higher network working pressures, and the degree of efficiency is only moderately satisfactory.